Valve-Sparing Aortic Root Replacement—“T. David V” Method

Positioning, lines, cannulation, and cardioplegic arrest. Under general anesthesia, the patient is positioned in the supine position with the chest/abdomen/pelvis and lower extremities prepped and draped in sterile fashion. A radial arterial line and central venous line with pulmonary artery catheter are standard. A median sternotomy is performed and the pericardium is opened widely. I tend to suspend the right portion of the pericardium but not the left. This allows the ventricular mass of the heart to fall downward into the left chest and provide better exposure to the aortic valve. Following systemic heparinization, standard aortic and two-stage right atrial cannulation is undertaken. An aortic cannula is used that will fit into the Dacron side arm of the graft that will be used for the hemiarch replacement. Both an antigrade and a retrograde cardioplegic catheter are placed to first arrest the heart antigrade with blood cardioplegia and then switch to retrograde cardioplegia during the remainder of the procedure. This is supplemented with topical iced saline for cooling of the heart. The myocardial temperature is monitored with a probe placed just right lateral to the left anterior descending coronary artery and angled into the interventricular septum. Interventricular septal temperature is maintained between 10 and 15°C for the entire cross-clamp procedure with intermittent 250 to 500 mL retrograde cardioplegic infusions every 20 minutes. For venting, a 14-F vent is placed directly in the apex of the left ventricle. Once on bypass, the patient is systemically cooled to a bladder temperature of 20°C.

Exposure. The superior margin of the right ventricle and right ventricular outflow tract are retracted downward and to the left, respectively, using needled silastic sutures anchored under a reasonable amount of tension. As the aortic root dissection proceeds, the silastic sutures recoil and provide dynamic exposure. Following cardioplegic arrest, the ascending aorta is transsected and the aortic valve is carefully inspected to ensure that it is a morphologically normal structure with no significant calcifications, fenestrations, or tears.

Coronary buttons, completion of aortic resection, and root dissection. The left and right coronary buttons are excised and gently retracted with 4-0 polypropylene sutures (A). Following completion of this, the residual aorta is carefully trimmed, leaving the aortic annulus and valve encircled by approximately 7 to 8 mm of native aorta. Next, a very careful dissection is undertaken separating the aortic root from the pulmonary artery, right ventricular outflow tract, and the left atrium (B). This dissection must proceed down to the level of the aortic annulus circumferentially and slightly below it if possible. The very unusual case where it is not possible to get down below the annulus due to structural issues with the heart is perhaps the only indication (in my mind) for a remodeling aortic root operation.

Graft sizing. Hegar dilators are carefully placed across the aortic valve to a dilator size that fits comfortably in the outflow tract but not tightly. Then 5 mm (accounting for 2.5 mm on either side of the outflow tract) is added to the dilator number and an additional 6 mm to allow for billowing of the graft (11 mm total). The result is a graft size that usually varies between 32 and 38 mm.

Subannular suture placement. A total of 12 to 15 multifilament 2-0 polyester sutures are placed in horizontal mattress fashion under the annulus such that one horizontal mattress suture is placed under each commissure. The sutures must be placed in as planar a fashion as possible and not ride up the commissures. Use an equal number of stitches for each sinus if they are roughly equal in size. Make sure that the sutures do not breach the aortic endothelium but all stay buried beneath it. Many authors place sutures up into the non-right commissure to prevent heart block. As shown here, I do not do this and have never seen heart block.

Graft placement. The previously sized Dacron graft is brought into the operative field and a marking pen is used to mark the graft at approximately 120° intervals. The horizontal mattress sutures are then placed sequentially through the graft (A). When this is completed, the graft is lowered into position such that the valve and all of the aortic tissues sit firmly within the graft. Great care must be taken to make sure that all layers of the aorta are sitting inside the graft before the sutures are tied (B). If part of the residual aorta (especially in the belly of the sinus) gets caught, pulling this through later will result in a loose annular reinforcement, which may predispose to bleeding acutely or lead to subsequent annular dilation chronically. The Hegar dilator that was used to size the annulus is gently placed across the valve before tying the sutures (C). The three subcommissural sutures are tied first, creating a small graft plication under each commissure that has the effect of narrowing the valvular commissural angle, an important step to achieving valve competence and durability of the repair. The remaining sutures are then tied firmly but not snugly all the way around, still keeping the Hegar dilator in place to prevent narrowing of the left ventricular outflow tract. Following suture tying, there should be a small amount of resistance felt when removing the Hegar dilator. Usually at the completion of this step, the patient's bladder temperature has reached 20°C, cold enough to effect circulatory arrest for the distal hemiarch anastomosis.

Hemiarch replacement. Preparation for circulatory arrest includes placing the patent in the Trendelenburg position, packing the head in ice, and administering 15 mg/kg IV of sodium pentobarbital and 1 g IV methylprednisolone. I select a woven Dacron graft sized 2 to 3 mm larger than the Hegar dilator used to size the graft for the valve-sparing root replacement, usually resulting in a 26- or 28-mm graft. The graft that I use has a 10-mm side branch. The pump is discontinued and the aorta is quickly resected. The trimmed graft is brought into the operative field and the anastomosis is performed with a running 3-0 polypropylene suture such that the side limb of the graft points directly anterior. A small amount of biological glue is used to seal needle holes. Pump flow is commenced at 1 L/min and the side limb of the graft is cannulated. The side limb, arch, and graft are carefully de-aired before the cross-clamp is applied to the graft just proximal to the entrance of the side limb. The hemiarch anastomosis is inspected for leaks as cardiopulmonary bypass is brought back up to full flow. When surgical hemostasis is obtained, rewarming is begun and the residual graft is folded under the innominate vein for later graft-to-graft anastomosis. Attention is turned back to the valve-sparing aortic root replacement.

Placement of the aortic valve commissures. 3-0 Polypropylene sutures are placed in horizontal mattress fashion from inside to out anchoring the tops of the valve commissures to the graft at 120° intervals. To achieve the appropriate graft height, put gentle traction on the graft to slightly unravel its corrugations before placing the sutures. Check at this point that these commissural attachment sites will not obstruct the direct re-implantation of the coronary arteries. The aortic root is irrigated with a small amount of cold saline and the valve leaflets are inspected to ensure coaptation on the same plane with no prolapse into the left ventricular outflow tract. If significant prolapse occurs or one particular leaflet is not coapting on the same plane the others, first consider re-siting the valve commissure on the graft to either stretch or relax the leaflet as required. Failing this, the leaflet is then suspended as shown in Figure 9B. The commissural suspension sutures are then gently tied with three knots, each leaving two equal lengths of suture loaded with a needle. SVC = superior vena cava.

Suturing the aortic valve to the graft. One limb of one polypropylene suture is then brought from outside to in just over top of the aorta surrounding one commissure. The aortic cuff around the valve is sutured carefully to the graft in running fashion (A). Care is taken not to take excessive bites of the graft and that the bites are taken very close to the annulus of the aortic valve to prevent subsequent dilation of both the annulus and the intervening aortic segment. Following completion of running of one of the commissures, the suture is brought outside and tied to one of the other Prolene sutures that are anchored to the other commissure. These two are cut and then the remaining suture on that side is used to run the next commissure and so on until this is completed. To deal with a prolapsing leaflet, a 6-0 polytetrafluoroethylene (Gore-Tex) suture is doubly run in continuous fashion along the free margin of the leaflet reinforced with small pledgets placed on the outside of the graft.¹³ This suture is tied when traction on it pulls the free margin of the valve leaflet up to the same level as the other two leaflets (B).

Implantation of the coronary arteries. An ophthalmic cautery is used to create appropriately sized defects in the left and right neo-sinuses of the graft for re-implantation of the coronary arteries, performed with 5-0 polypropylene suture. Following completion of these two anastomoses, the operation is carefully inspected from the inside to make sure that the suture lines on the coronaries are uniform and hopefully will not leak. A small amount of biological glue may be distributed outside over the anastomoses to seal needle holes. a. = artery.

Graft-to-graft anastomosis. Following completion of this portion of the operation, the graft is then trimmed to approximately 5 mm (ie, three or four graft corrugations) above the implanted aortic valve commissures. The previous graft used for the hemiarch anastomosis is unraveled, measured, and trimmed appropriately. The graft-to-graft anastomosis is then constructed with running 3-0 polypropylene suture. It is important to understand that the graft used for the hemiarch replacement is smaller in diameter than the graft used for the valve-sparing aortic root replacement so care must be taken to appropriately adjust the needle bites in the two grafts so that the larger proximal graft will telescope down to create a uniform neo-sinotubular junction.

Weaning from bypass and hemostasis. An ascending aortic vent with a cardioplegia infusion line is inserted in the graft and 500 mL of warm cardioplegia is given with the first 100 mL used to de-air the root. The ventricular vent is removed and oversewn with a running 2-0 polypropylene suture. The retrograde cardioplegic catheter is removed. Ventricular and atrial pacing wires are placed. The cross-clamp is removed and sinus rhythm is allowed to resume. During myocardial recovery, careful interrogation of the valve is undertaken by transesophageal echocardiography to assess for any residual insufficiency and to measure the coaptation distance of the valve leaflets. One should aim for a coaptation distance of 5 mm or more. When this can be achieved, this operation is likely to be very durable. I will accept “trivial” aortic insufficiency. If any more than this is encountered, consider re-arresting the heart and inspecting the repair. If the reason for the insufficiency is not identified or not repairable, it may be necessary to excise the leaflets and replace the aortic valve with either a mechanical or a tissue prosthesis depending on the preferences expressed during preoperative discussions with the patient. Following an appropriate period of rewarming (to at least 36.5°C) and de-airing, the ascending aortic vent is removed and this site is reinforced with a 4-0 polypropylene suture. The patient is then weaned from cardiopulmonary bypass. The venous cannula is removed. Protamine administration is given directly down the side limb of the hemiarch graft. Following completion of protamine administration, the side graft is then tied at its point of insertion into the larger graft with two no. 2 silk ties. The graft is then divided, resulting in arterial separation from bypass. This is a relatively lengthy operation with long cross-clamp times in the range of 80 to 140 minutes. There are many suture lines and, as such, it is not unusual to wean from bypass and have a considerable amount of bleeding. A careful inspection of the suture lines should have taken place while on bypass to eliminate any surgical causes of bleeding. Following weaning from cardiopulmonary bypass, protamine is administered and the repair is tightly packed for 5 to 10 minutes. During this time, appropriate platelet, fresh frozen plasma, and cryoprecipitate infusion should be undertaken relative to the patient's laboratory values. On pack removal, the majority, if not all, of the suture lines should have ceased bleeding. If the patient is coagulopathic, repacking and infusion of blood products is appropriate as deemed by laboratory testing. If the patient is completely warm, if all laboratory values are normalized, if all surgical bleeding is controlled, and if bleeding has still not ceased, it is appropriate at this point to consider infusion of recombinant activated factor VII concentrate.

Bicuspid aortic valve. The operation proceeds as for a tricuspid valve with a few caveats. First, there is often a size discrepancy between the two fused leaflets and the remaining unfused leaflet. All commissures may be unequal in height, and the fused commissure is almost always lower than the other two (or sometimes absent). In addition, the commissures in a bicuspid aortic valve are usually not oriented at 120° intervals. This geometry must be taken into account and incorporated when orienting the valve inside of the graft. Also, the fused valve leaflets create a shelf, which can make placing sutures under the annulus difficult in this area. One must be persistent and retract the fused leaflet gently for visualization. Do not rush this step, because it is possible to tear the leaflets or tear the aorta. Finally, with bicuspid aortic valves, coronary arteries tend to be oriented almost 180° from each other and can originate very close to the valve commissures or annulus (A). Usually, with great care, the coronary arteries can be separated from the valve with enough of an aortic cuff on either side to allow re-implantation. This, of course, means that there is a finer margin of error in placing the commissures in the correct locations within the graft to prevent difficulties in re-implanting the coronary arteries later. However, occasionally the coronary ostium originates so close to the valve annulus that it cannot be separated. In these cases, the coronary ostium is left in situ and the perivalvular aortic cuff is excised around and including the coronary ostium. Next a “keyhole” slit is cut in the implanted graft that will allow the coronary artery to pass into the graft and sit comfortably with no obstruction.¹⁴ Several interrupted 4-0 poly propylene sutures are used to close the slit under the coronary artery. The valvular aortic cuff is sewn to the inside of the graft as outlined in Fig. 9. Then, an “in-and-out” 5-0 polypropylene stitch is used to anchor the coronary artery to the graft with the knot tied on the outside (B). a. = artery.